Instructional device for calculating



June .1952 s. H. SVENSSON INSTRUCTIONAL DEVICE FOR CALCULATING Filed May 20, 1950 $225; w Y m N INVENTOR 5 Men /m r Svensson ATTORNEY Patented June 10, 1952 "OFFICEQT INSTRUCTIONAL DEVICE FOR,

. CALCULATING Sven Hjalmar Svensson, Alingsas, Sweden Application May 20, 1950, Serial No. 163,109 '0 In Sweden March 8, 1947 2 Claims. 1

This invention relates to improvements in devices for illustrating and teaching the elementary technic of calculating, and the object of the invention is to provide a device of said kind which is particularly suitable for use in instructing children in the primary school stage.

The invention will be explained more clearly in the following description, reference being made to the accompanying drawing showing, by way of example, two embodiments of the invention.

Fig. 1 shows a plan view of an instructional device constructed in accordance with the invention.

Fig. 2 is a section on line II-II in Fig. 1.

Fig. 3 shows a modifiedperformance of a detail in Fig. 1.

As will be seen from the figures the instructional device comprises two strips I and 2, strip I being provided with a scale 3. To the strips I and 2 are attached two plates 4 and 5, plate 5 being provided with apertures or holes 8 arranged in two rows. Between the plates 4 and 5 are slidably provided two further plates 1 and 8, each of them being provided with an operating member 9 and I respectively, said members protruding through a slot II provided in the upper plate 5. The left end, as shown in Fig. l, of each plate I and 8 is provided with a recess I2 and a projecting tongue I3 in such a manner that the plate in certain positions exposes a number of holes in the upper row of holes, which number by one unit exceeds the number of holes exposed in the lower row, while in other setting positions the number of holes exposed in the two rows is equal.

Immediately adjacent to the strip I the plate is provided with a slot I 4 in which the end margins of the plates I and 8 are visible.

The lower, fixed plate 4 is provided with a covering layer of a material the colour of which differs from the colour of plate 7, the colour of said last-mentioned plate in turn also difiering from the colour of plate 8 and the upper surface of plate 5. For instance, the layer I5 may be red and plate 1 green, whilst plate 8 and the upper surface of plate 5 are white.

In the embodiment shown the holes 6 are divided into two groups comprising ten holes in each group, said groups being marked by borderlines I6. These groups, consequently, are easy to recognize. Now, if, as for instance in the example shown, it is desired to illustrate the addition 5+8, plate I is set in such a manner that its edge visible in the slot I4 coincides with line 5 01' the scale 3, five holes being exposed within the left border I6., The holes of said border will then appear in a red colour. Due to the location of the operating members 9 and III the plate 8, upon this primary displacement, will be taken along with the movement to the right from the original position which is assumed to be the left end position. Thereafter plate 8 is moved, thereby exposing eight further holes, five of them lying within the left border I6 and three of them within the right border I6, the end margin of plate 8, which is visible in the slot I4, being located close to line I3 of scale 3. The eight last exposed holes then appear in a green colour.

According to Fig. 3 the covering layer I5 is provided with a scale I! appearing in the slot I4, which scale agrees with the scale 3 on the strip I. Further, in a corresponding manner, the plate I is provided with a scale I8, so that, for instance, when carrying out addition of the numbers 5 and 3 these two numbers appear in the slot I4 whilst the sum may be read on scale 3.

It will readily be seen that the device also can be used for illustrating subtraction. If, as in the embodiment shown, the device is constructed in the form of a rule, obviously it will be convenient to use on scale 3 a graduation in measure of length. Instead of using different colours on the plates 4, I and 8 they may be provided with different patterns or may in any other suitable manner be made to distinguish from each other.

What I claim is:

1. A device for instructing adding and subtracting comprising two spaced-apart superposed plates secured to one another, the upper of said plates being provided with apertures, two additional superposed plates disposed between the first-mentioned two plates, said additional plates being slidable relative to each other as well as relative to the two first-mentioned plates and having surface appearances difi'ering from each other and being adapted upon slidably moving to expose the subjacent plate to view through varying numbers of said apertures, and the lower of the two first-mentioned plates having a surface appearance difierent from that of the other plates, so that upon slidably moving the intermediate plates relative to each other and relative to the two first-mentioned plates the apertures through which the subjacent plates are exposed to view are divided into two groups having appearances difiering from each other, the plates being provided with a scale for reading the sum of the apertures of the two groups.

2. A device for instructing adding and 'subtracting comprising two spaced-apart superposed 3 plates rigidly secured to each other, the upper oi. said plates being provided with holes, two additional superposed plates being provided between the two first-mentioned plates, said additional plates being slidable with respect to one another and also with respect to the two first-mentioned plates and having difierent surface appearances with respect to each other and being adapted upon slidably moving to expose the subjacent plates to view through varying numbers of the said holes, the lower of the two first-mentioned plates having a surface appearance differing from that of the other plates, so that, upon slidably moving the intermediate plates relative to each other and relative to the two first-mentioned plates, the holes through which the subjacentplates are exposed to view are divided into two groups having appearances differing from each other, the said plates being provided with scales for reading the number of holes exposed in each group and the sum of the holes of the two groups.

SVEN HJALMAR SVENSSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 7 941,733 Badanes Jan. 2, 1934 2,482,658 Culp Sept. 20, 1949 FOREIGN PATENTS Number Country Date 237,323 Germany Aug. 5, 1911 

